1. Plate Boundaries: The Action is at the Edges!

2. The Earth’s Plates The earth’s crust is made up of huge tectonic plates These plates are moved by convection currents in the Earth’s mantle layer, like rafts floating on thick liquid (like toothpaste or asphalt).

3. 3 Types of Plate Boundaries Plate boundaries are important to understand because they are where geological phenomena such as earthquakes, volcanoes, and tsunamis occur. There are 3 main types of boundaries: 1.Divergent 2.Convergent 3.Transform (transform-fault)

4. 1) DIVERGENT BOUNDARIES Almost all the Earth's new crust forms at divergent boundaries, but most are not well known because they lie deep beneath the oceans. Divergent boundaries are zones where two plates move away from each other, allowing magma from the mantle to rise up and solidify as new crust.

5. DIVERGENT BOUNDARIES Divergent boundaries most often occur on the ocean floor along the mid-ocean ridges.

6. Mid-Atlantic Ridge The Mid-Atlantic Ridge, which splits nearly the entire Atlantic Ocean north to south, is probably the best-known and most-studied example of a divergent plate boundary.

7. Iceland sits upon the Mid-Atlantic Ridge

8. A Divergent Boundary The western side of Iceland sits on the North American Plate and is moving toward the west. The eastern side of Iceland sits on the Eurasian Plate and is moving toward the east.

9. Thingvellir National Park On my trip to Iceland in July 2006, I visited Thingvellir National Park, located on the Mid-Atlantic Ridge!

10. Thingvellir I walked from the North American Plate to the Eurasian Plate

11. Iceland Geological Activity There are many amazing sites in Iceland like this boiling mud pit. The hot magma is so close under the earth’s crust that it’s a danger to visitors, who must obey the signs! Intense sulfur smell !

12. 2) CONVERGENT BOUNDARIES Occur when plates collide or push against each other. Sometimes one plate slides below the other. This is called subduction. As the more dense plate sinks into the mantle, it melts. The magma that forms from this melting plate may slowly rise & produce volcanoes.

13. CONVERGENT BOUNDARIES Sometimes the plates buckle and rise to form mountains. The Himalayan mountain range formed this way—when two plates collided.

14. Example: Himalayan Mt. Range 40-50 million years ago, two large landmasses, India and Eurasia, collided. The two plates had the same density, so one could not sink below the other. The pressure caused the plate edges to thrust upward toward the sky. The Himalayan mountains are still growing at a rate of 1 cm. per year.

16. 3) TRANSFORM BOUNDARIES At transform boundaries, plates grind past each other side by side. This type of boundary separates the North American plate from the Pacific plate along the San Andreas fault, a famous transform plate boundary that is responsible for many of California's earthquakes.

17. SAN ANDREAS FAULT

18. Diagram the Three Different Plate Boundaries 1.Draw large arrows showing the direction the plates are moving at the 3 different boundaries. 2.Write down an example of a location of each type of boundary.

19. Divergent Example: __________________________________

20. Convergent Example: ___________________________________

21. Transform (Transform-Fault) Example: ___________________________________